Can you clarify what you mean?

My local library is run by the county government, so of course the government can see the checkouts, they are the ones I check the book out from. But they restrict checkout information from others. For example, a parent can see the checkouts of their own children, but not after they turn 13.

Perhaps you're talking about subpoenas? Checking some other libraries I see SF Public Library has some discussion about that, but they delete books from your checkout history once they are returned. https://sfpl.org/about-us/confidentiality-and-usa-patriot-ac...